Science Diets

The results of scientific studies are often equivocal due to such aspects as the study population, the number of subjects, the study design and methods used to determine the outcome, and even who sponsors, or pays for, the study. Thus, two studies that examine the same issue can have wildly divergent results. For example, one study may find good results with a particular food supplement, such as increased muscle gains or bodyfat loss, while another study examining the same supplement may find negligible results. Such scientific flip-flops have led to the concept of the scientific method, in which a hypothesis, or presumption, isn’t proven until the findings are replicated several times.

One obvious problem with the scientific method, however, is that few sponsors are willing to foot the often-expensive bills to fund continuing studies unless there’s a definite profit potential. That’s the primary excuse the pharmaceutical industry uses to justify the usually exorbitant cost of patented drugs: It takes millions to fund the research needed to prove the efficacy of a drug, then get it approved. It’s patented to protect the drug company’s investment in research and development.

Luckily, not all scientific studies are that expensive, and when several of them are published, it’s possible to observe specific trends. The practice of compiling several studies to arrive at definite trends is known as a metanalysis, and for the past 15 years or so the cold eyes of science have been focused on bodybuilding nutrition, particularly the nutrient and health effects of various bodybuilding diets. The majority of such studies have been published in peer-reviewed journals and have not been tainted by connections to supplement companies or other parties that stand to gain financially from the outcome. As such, the studies are valuable.

Analyzing typical bodybuilding diets can point to the need’or lack thereof’of various types of food supplements. Studies can also evaluate the health aspects of such diets and may even provide information on the effects of possible confounding elements such as simultaneous drug use or exercise habits. Then there’s the curiosity aspect: Just how do competitive bodybuilders eat? What types of foods and meals are best for losing bodyfat and maintaining muscle? Or, conversely, what do male and female bodybuilders do wrong in relation to their eating habits? What could they do to improve their present eating styles?

Nutrient Content of Bodybuilding Diets

One problem with most of the published studies that have evaluated bodybuilding nutrition is that they have nearly always examined precontest diet regimens. Such fare differs dramatically from off-season eating simply because the goals of precontest dieting involve eliciting extreme changes in body composition.

Most competitive bodybuilders want to lose as much bodyfat as possible without sacrificing hard-earned lean mass or muscle. In their attempt to accomplish that, they show little concern for nutrient intake. In the interest of achieving the calorie deficit required for effective fat loss, they stop eating so many foods, they’re bound to run into nutrient intake problems. For example, one study of male bodybuilders found that the average number of different foods consumed dropped 30 percent during the precontest training phase.1

A study of college-age female bodybuilders found that the subjects limited food intake prior to a contest to chicken, tuna, egg whites, brown rice, rice cakes and pasta while avoiding egg yolks, red meat and dairy foods.2 The study focused on 10 women, six of whom were preparing for competition. Analysis of the competitors’ diets revealed that they were taking in less than 66 percent of the recommended daily allowances (RDAs) for vitamins B12, D, E and folic acid. As for minerals, they were getting less than 66 percent of the RDAs for calcium and zinc, probably because they’d stopped eating dairy foods and meats.

Another study examined the diets of 11 female and 13 male competitors who were preparing for the NPC USA Championships.3 The results showed that the nutrient ratios for female competitors averaged 39 percent protein, 12 percent fat and 48 percent carbs. For male competitors the figures were 40 percent protein, 11 percent fat and 49 percent carbs. Female competitors got less than the RDAs for calcium, zinc, copper and chromium, and they took in no vitamin D at all. One of the male bodybuilders ate nothing but 6 1/2-ounce cans of tuna five times a day. That provided him with 1,930 calories, of which 97 percent came from protein. His carb intake was zero.

Most of these studies were conducted during an era when fat was considered taboo. Thus, the diets contained an average of only 5 to 10 percent fat, with the exception of one that included an average of 36 percent fat, mainly because the bodybuilder ate 81 whole eggs a week.4 Most bodybuilders eat only egg whites, discarding the yolks. While that does eliminate the fat content, it also wastes half the protein content of the egg and all of the vitamins and minerals found only in the yolk.

In recent years the importance of including fat in the diet has received more prominence, and most competitive bodybuilders’ diets today feature at least 20 percent fat. That also relates to findings about the relationship between dietary fat intake and maintenance of serum testosterone levels. Such studies show that it takes a minimum of 20 percent of calories coming from fat to maintain optimal testosterone synthesis. Studies show that even saturated fat will work for that purpose, although saturated fat is also related to an increased risk of insulin resistance, which would interfere with bodyfat reduction.

As a result, the type of fat recommended for both health and bodybuilding purposes is mainly monounsaturated fats, such as are found in canola oil, peanuts, macadamias and other foods, and the essential fatty acids linoleic and alpha-linoleic acid, which are found in omega-6 and omega-3 fat sources. Typical omega-6 fat sources include most vegetable oils, while omega-3 sources include fatty fish, such as halibut, salmon and mackerel. People who have an aversion to fish can get alpha-linoleic acid from flaxseed oil and English walnuts, although the conversion to the primary omega-3 fats (EPA and DHA) isn’t as efficient as it is when you get them by eating fish or taking fish oil supplements.

The emphasis on dietary fat is a recent phenomenon. Nearly all the studies that have analyzed bodybuilding diets noted extremely low fat intakes. When they were performed, the only commonly used fat supplement was medium-chain triglycerides (MCTs). A typical diet from that era was featured in a case study of the diet and training regimens used by Michael Ashley that was published in a nutrition journal.

Ashley won the Arnold Schwarzenegger Classic in 1990 and the World Amateur Championship in 1986, both of which were drug-tested contests.5 That’s significant, since he was a vehement advocate of natural bodybuilding. I interviewed Mike on several occasions and even witnessed him preparing his meals. I can attest to the fact that I’ve never seen a bodybuilder, before or since, who was as precise’nearly obsessive’about his nutrition as Ashley was. He refused to eat in restaurants, since he distrusted what they might add to the food, such as sodium or other additives. He always weighed and measured every morsel of food that he ate. He also kept concise food logs so he could analyze his diet changes.

The study of Mike’s contest preparation noted that he took in just under 5,000 calories a day, 1,278 of which were derived from medium-chain-triglyceride supplements. Excluding the MCTs, his diet contained 76 percent carbohydrate, 19 percent protein (1.9 grams per kilogram of bodyweight) and only 5 percent fat. His carb intake was far greater than is common today, while his fat intake (minus the MCTs) was much lower. Yet his diet provided 100 percent of the RDA for all nutrients with the exception of zinc and calcium, which were missing because Ashley avoided foods rich in those nutrients, such as red meats and dairy foods.

Ashley weighed 209 off-season and 195 pounds in contest shape at a height of 5’7 1/2′. His intake of nearly 5,000 calories seems high for a man his size, unless you examine his activity level. He trained six times a week for three hours and also did two hours of aerobics daily. His diet consisted of brown rice, oatmeal, potatoes, yams, beans, corn, peas, carrots, broccoli, green beans, lettuce, blueberries, chicken, fish and egg whites. He also drank small amounts of milk. Although his diet appeared to contain adequate carbohydrate in the form of fruits and vegetables, as well as rice and oatmeal, Ashley took a carbohydrate supplement three times a day to maintain his glycogen levels. He also took 12.8 grams a day of amino acids, representing 7 percent of his total protein intake.

If Ashley used the carb supplement with the amino acids after he trained, he was ahead of his time. In recent years it’s become evident that combining carbs with a readily available, fast-acting protein source (such as amino acids or whey) significantly increases muscle glycogen replenishment and muscle recovery. It accomplishes that by boosting insulin release following training, thus promoting glycogen synthesis by way of enzymatic induction. The amino acids not only promote muscle protein synthesis following training, but they also impart an additive insulin-promoting release that boosts the effect of ingested carbohydrate.

In retrospect, Ashley’s reliance on MCT oil as an energy source (it does contain about 8.2 calories per gram) may not have been a good idea. No doubt he relied on it because of MCT’s reputation for acting more like a carbohydrate due to its rapid absorption and utilization properties; however, those same attributes also predispose the body to burn ingested MCT in preference to stored bodyfat. As a result, MCT may inhibit bodyfat losses. On the other hand, Ashley may have relied on MCT as an additional source of calories to fuel his intensive workouts and spare muscle tissue, in which case his use of MCT was correct.

Ashley’s diet was atypical of most bodybuilding diets that have been surveyed in the medical literature, since he ate a large variety of foods. As such, he likely minimized his need for food supplements. His diet was low in zinc and calcium, but Ashley easily remedied that by taking mineral supplements.

Other studies confirm that bodybuilders, particularly during the precontest phase of training, cut out many healthy, essential foods, usually including fruits, vegetables and dairy products.6 They stop eating fruits and vegetables because of the notion that they contain too many carbs, while the rationale for avoiding dairy products is less clear, since nonfat dairy foods don’t contain a lot of carbs and have little or no fat.

While Ashley was a natural bodybuilder who refused to use any type of anabolic drug, another case study focused on a 27-year-old amateur bodybuilder who did use various anabolic steroids.7 He also trained six times a week and did an hour of aerobics daily. The bodybuilder used six different anabolic steroids, both oral and injectable, as well as Aldactone, a potassium-sparing diuretic, to prevent excess water retention. To prevent his body from suppressing its natural testosterone production, he injected himself with human chorionic gonadotropin (HCG), perhaps being unaware that it also promotes increased estrogen production, especially when taken simultaneously with certain steroid drugs.

The bodybuilder’s diet contained 2,094 calories a day, of which 26 percent was protein, 56 percent carbs and 18 percent fat. Similar to Ashley’s program, his diet met most of the nutrient RDAs (80 percent) with the exception of zinc and calcium. During the final precontest week he reduced his carb intake to 11 percent of calories for one day, then increased carb intake to 57 percent, then 73 percent of total calories, thus using carb loading in an effort to produce fuller-appearing muscles. The practice of carb loading still exists today, although its effectiveness has always been doubtful.

The carb-loading procedure begins with a short period’two to three days’of carb depletion, followed by another two to three days of increased carb intake. The idea is to deplete the muscles of glycogen by restricting carbs, then hope the body will compensate with higher-than-usual glycogen stores when you take in additional carbs during the second phase of the carb load. Several studies that have measured the purported gains made with carb loading have found that the technique merely replaces the glycogen and water lost during the carb-restricted phase. Any perceived gains are thus strictly illusory.

An interesting aspect of the case study of the amateur bodybuilder is that he lost 2.3 kilograms (about five pounds) of lean mass, despite using a typical anabolic steroid stack. The researchers who analyzed his diet and training attribute the muscle loss to a rapid loss of weight, averaging 4.2 pounds a week. The suggested weight-loss rate to protect muscle loss is one to two pounds a week, which suggests that precontest diets are most effectively begun well in advance of an impending contest, with the precise start date dependent on existing body composition; that is, the more bodyfat, the earlier you should begin your diet.

Bodybuilders are known to advocate dietary supplements. One study found that of 76 bodybuilders surveyed, 63 percent used some type of food supplement.8 One subject took 87 pills daily, while 59 percent used protein supplements. The researchers noted that the bodybuilders’ average protein intake was 2.2 grams per kilogram of bodyweight from food alone, which made additional protein supplements superfluous. They also noted that 39 percent of the bodybuilders took vitamin-and-mineral supplements, despite the fact that they were getting the RDA for the nutrients from their food. Because of that, the authors felt that such extensive supplement use wasn’t justified.

One thing to consider about this study was that none of the surveyed bodybuilders were on a precontest diet. As such, they likely ate a large variety of foods, which explains their nutrient intake. As discussed, that’s not the case with the typical restricted precontest diet, which usually eliminates entire classes of foods. Considering that bodybuilders follow such diets for up to three months or more, it becomes mandatory for their health that they use supplements to supply missing essential nutrients.

In addition, lowfat diets’which are still much in vogue today’can increase the risk of deficiencies in essential fatty acids as well as lower the synthesis of anabolic hormones such as testosterone. Studies show that many people’not just bodybuilders’don’t get enough omega-3 fats, which are found mainly in fatty fish sources. Considering that the brain is composed of 40 percent of that type of fat, it’s easy to see the emerging relationship between the increased incidence of psychological disturbances like depression and the lack of dietary substances such as omega-3 fats. That, of course, is especially problematic for bodybuilders who avoid fattier fish sources, such as salmon, and instead rely on leaner types of fish that don’t contain adequate levels of omega-3 fatty acids.

Studies also point to the relationship between increased exercise-induced oxidative muscle damage and exercise recovery, which makes nutrients such as vitamin E and selenium important for bodybuilding recovery. Foods that are rich in vitamin E, such as vegetable oils, not only supply relatively tiny amounts of the vitamin, but they also aren’t typically consumed in any meaningful quantities by bodybuilders because of their high calorie counts. The fact that many competitive bodybuilders eliminate other foods, such as fruits and vegetables, necessitates that they get the nutrients contained in the foods from supplements. Let’s face it, a precontest bodybuilding diet is anything but a nutritionally balanced program.

As for protein, it’s true that bodybuilders tend to eat more protein than the average person; however, research has shown that you must increase protein intake as you reduce calories to offset lean tissue losses. Protein supplements provide a low-calorie, low-carb, nearly zero-fat source of concentrated, high-quality protein, which gives you tight control on your calories while providing the necessary additional protein. Also consider the many studies showing that protein-and-carb combinations increase muscle recovery when consumed shortly after training.

Newer food supplements, such as creatine and ribose, weren’t available when most of the existing bodybuilding diet surveys were published. Nevertheless, it’s safe to assume that most bodybuilders do use creatine, due to its effectiveness in increasing muscle energy stores. In fact, a recently published study found that using supplemental creatine during energy restriction, such as dieting, effectively maintained muscle energy stores and helped to maintain exercise intensity.9 Ribose, which the body needs for the synthesis of ATP, the most elemental muscle energy source, likely helps creatine in that task.

The existing database of typical bodybuilding diets indicates that precontest diets are notably lacking in many essential nutrients. You need to experiment to find the balance of nutrients that works best for you. Contrary to many claims, no one diet works best, although all feature some reduction of calories. People who have higher bodyfat levels will likely get better results with diets featuring a lower carbohydrate content. People who have enlarged fat cells tend to have some degree of insulin resistance, and the increased insulin control typical of low-carb diets will effectively help them tap into stored fat deposits.

On the other hand, extensive research documents the health benefits of phytochemicals found in various fruits, vegetables and legumes that are not often available in supplement form. They offer protective effects against cardiovascular disease and cancer, which are the primary causes of death in the world. You should never eliminate such foods from your diet year-round, since it’s a health risk. Too much of anything is risky, and moderation is usually the best course to follow in all things, including diets.

Sample Diet

Meal 1
Milk (2%), 8 ounces
Protein powder (stirred into milk)
3 rice cakes with peanut butter (2 tablespoons)

Meal 2
Meal replacement, such as Muscle Meals

Meal 3
Roasted skinless chicken, 8 ounces
Green vegetable, 6 ounces
Rice, 1 cup

Meal 4
Cottage cheese (regular), 8 ounces
Pears (canned in own juice), 4 halves

Meal 5
Meal replacement, such as Muscle Meals

Meal 6
Tuna sandwich on whole-wheat bread
(1/4 cup tuna packed in water)
Apple
Peanuts (handful)

References

1 Sandoval, W.M., et al. (1991). Food selection patterns of bodybuilders. Int J Sports Nutr. 1:61-68.

2 Lamar-Hildebrand, N., et al. (1981). Dietary and exercise practices of college-age female bodybuilders. J Amer Diet Assoc. 89:1308-1310.

3 Kleiner, S., et al. (1994). Nutritional status of nationally ranked elite bodybuilders. Int J Sports Nutr. 4:54-69.

4 Faber, M., et al. (1986). Dietary intake, anthropometric measurements and blood lipid values in weight-training athletes (bodybuilders). Int J Sports Medicine. 7:342-346.

5 Manore, M., et al. (1993). Diet and exercise strategies of a world-class bodybuilder. Int J Sports Nutr. 3:76-86.

6 Vega, F., et al. (1996). Dietary habits of bodybuilders and other regular exercisers. Nutrition Research. 16:3-10.

7 Hickson, J.F., et al. (1990). Nutrition and the precontest preparations of a male bodybuilder. J Am Diet Assoc. 90:264-267.

8 Faber, M., et al. (1987). Nutrient intake and dietary supplementation in bodybuilders. S Af Med J. 72:831-834.

9 Rockwell, J., et al. (2001). Creatine supplementation affects muscle creatine during energy restriction. Med Sci Sports Exercise. 33:61-68. IM